Motor vehicle braking mechanism



w. R. GRlswoLD 2,127,294

i MOTOR VEHICLE BRAKING MECHANISM Filed July 26, 1934 2 Sheets-Sheet lwww;

Aug. 16,1938.

Aug. 16, 1938. w. R. GRISWOLD `IOTOR VEHICLE BRAKING MECHANISM FiledJuly 26, 1954 2 Shets-Sheet 2- 'Q @77 5 110 z V Patented Aug. 1.6, 1938UNITED STATES PATENT oFFlcE Packard Motor Car Company, Detroit, acorporation o! Michigan inch.,

Application July 26, 1934, Serial No. '137,026

27 Claims.

'Ihis invention relates to motor vehicles and more particularly tosuspension mechanism for motor vehicles. l

It is customary in motor vehicles to provide i spring suspension meansbetween the wheel carrlers and the body supporting iframe.v Motorvehicles are also generally equipped with shock absorbers which can beregulated to vary the re sistance offered to vertical movement of thewheel carriers and the frame relatively.

In order that the ride in the vehicle will be comfortable, it iscustomary to have the springs relatively flexible, or soft, and to setthe shock absorbers so that they resist spring deflection only ,6 anecessary amount. With such vehicle suspension, application of thebrakes tends to cause 'the body to move downwardly at the front end,that is to dive, and the amount of diving varies in accordance with theiiexibility of the suspension sys- 50 tem. This diving of the body isobjectionable from a standpoint of riding comfort and it is dangerousbecause of dimculty in steering at such times as it occurs.

An object of this invention is to provide a ve- 55 hicle suspensionsystem having flexibility without the above mentioned objectionsoccurring when the brakes are applied.

Another object of the invention is to provide a motor vehicle suspensionsystem in which shock- 30 absorber resistance to vertical movementbetween the body and the wheels relatively is increased duringapplication of the brakes.

Still another object of the invention is to provide hydraulic shockabsorbers for motor vehicles 35 in which the fluid flow is regulated bythe brake applying and releasing mechanism.

Other objects of the invention will appear from the followingdescription taken in connection with the drawings, which form a part ofthis specica- 4.0` tion, and in which:

Fig. l is a plan view, partly in section and partly broken away, of amotor. vehicle chassis having my invention incorporated therewith;

Fig. 2 is a side elevational view of the forward 45` end of the samewith one of the wheels broken away in order to more clearly illustratethe suspension system;`

Fig. 3 is a plan view, partly broken away and partly in section, lookingat the bottom of a front 50 shock absorber as assembled in Fig. 1;

Fig. 4 is a sectional view of a shock absorber taken on line 4-4 of 3;

Fig. 5 is an end elevational view of a front shock absorber, partiallybroken away to illustrate one 55 of the control valves;

(Cl. 18S-2) Fig. 6 is a sectional view taken on line 8-6 of Fis- Fig. 7is a sectional view taken on line 'l--l oi Fig. 5.

Referring now to the drawings by characters of reference, side sills llland cross brace members l I form a relatively rigid notor vehicle mainframe. Associated with the frame are front steering road wheels l2 andrear traction road wheels I3, the last mentioned wheels having drivemechanism within the axle housing Il connected therewith in aconventional manner.

Between the frame and the road wheels is pro-p vided a suspension systemconsisting generally of spring means and fluid shock absorbers. The rearaxle housing It is fixed to a central portion of a pair oflongitudinally extending leaf springs i5, such springs being connectedto the side sills Il] in the conventional manner.

The steering wheels are shown as independently connected with the mainframe. Each wheel supporting structure includes an axle yoke l 6 towhich a knuckle il is pivotally connected by a king pin i8, the knucklebeing provided with the usual spindle on which the wheel is rotatablymounted. A pair of superposed connectors I9 and are plvoted at one endto each yoke, the upper connectors I9, which are in the form oi links,being pivoted at their inner end to the adjacent side sill oi' theframe. The lower connectors *20' are triangular in form, each having aleg 2| pivoted at its end to the front cross frame member and arearwardly extending leg 22 pivoted to the adjacent side sill of theframe. A bracket 23 projects laterally irom each side sill above thelower connectors 20 and coil springs 24 are mounted therebetween.

Between the rear axle Il and the side sills of the main frame are shockabsorbers 25 which Vcan be of any conventional type but are preferablyof the hydraulic type. Between each steering wheel supporting structiu'eand an adjacent portion of the main frame ls arranged a shock absorber26 having an adjustable feature whereby resistance to vertical movementof the frame and the wheels respectively can'be varied or substantiallyshut off.

The same characters of reference will apply to both front shockabsorbers and I will now describe one of them. The casing 30 is formedwith two laxially aligned .horizontally extending chambers 3l and 32 inwhich pistons 33 and 34 are mounted for reciprocation. The pistons aresecured to move in unison by means oi a connector and between theadjacent ends oi the pistons is a cam head 36 forming one end of shaft31 which projects through the wall of the casing. The shock absorber isfixed to the main frame by means of bolts 36 which pass through openingsin brackets 39 projecting from the casing. An arm 40 fixed to the end ofthe shaft projecting from the casing and a link 4| connects the arm withthe axle yoke I6. Relative vertical movement of the frame and frontwheel supporting structures will transmit a similar movement to links 4|which will rock the shaft and turn the cam end thereof so that thepistons will be reciprocated in the casing.

Communication is established between the ends oi' the chambers 3| and 32through a series o1' passages and valve means located in and carried bythe shock absorber casing. A passage 42 leads from the chamber 32 and apassage 43 leads from the chamber 3 I. 'Ihe passage 42 joins the passage44 extending parallel with the axis of the chambers while the passage 43connects with an angular passage 45 extending substantially transverselyto the axis of the pistons. A pair oi chambers 46 and 41 are formed inthe end of the casing adjacent the passage 43 and are connectedtherewith by the passage 46. T'hese chambers are closed at their outerends by screw plugs 49 and 56 which are axially adjustable in the endwall of the casing. The chamber 41 is connected with the valve chamber5| by means of a passage 52 and leading from the chamber 46 to the valvechamber 5| is a passage 53. The passage 44 also connects with the valvechamber 5| and the valve 54 in such chamber is formed to controlcommunication between the passage 44 and the passages 52 and 53 so thatflow between the chambers 3| and 32 will be either established or cutoff. The valve 54 is rotatably mounted in the chamber 5| and an end 55projects exteriorly o1' the casing for the purpose oi' connection withadjusting mechanism, a suitable bushing 55 being employed to retain thisvalve axially in the casing. The valve is formed with a circular recess56 which is open to the passage 44 and it is also provided with anaxially extending slot 51 of sumcient length to establish communicationbetween the passages 52 and 53, such slot intersecting the annulargroove. It is obvious that rotation o1' the valve 54 will establishcommunication between the passage 44 and the passages 52 and 53 or itwill cut off such communication.

In the chamber 46 is a valve member 56 having a head engaging theshoulder at the junction of the passage 53 and the end of the chamberadja'- cent thereto, such valve being normally seated Vby a coil spring59 which is held in compression through engagement with the valve headand a washer or retainer 60 bearing against the inner end of the plug49. There is a similar valve 6| in the chamber 41 and it is providedwith a head portion which engages the shoulder at the junction of thepassage 52 and the chamber 41. This valve also has a head normallyseated by a spring 62 which bears against the valve head and a washer orretainer 63 seated against the inner end o! the plug 50. 'I'hese valves56 and 6| open and close in the same direction but the spring 62 exertsmuch greater force than does the spring 59.

Communicating with the chamber 41 is a passage 64 which leads to achamber 65 closed at its outer end by an axially adjustable screw plug66. The passage 52 and the chamber 65 are connected by passage 61. Inthe chamber 55 is a valve 66 which seats against the shoulder formed bythe junction between the chamber 65 and the passage 64, such valve beingnormally held closed by a spring 69 which engages the valve head and aretainer 16 bearing against the inner end of the plug 66. The forceexerted by this springis simllar to that exerted by the spring 62. 'Ihisvalve 63 opens in a direction opposite to that in which the valves 53and 6| open.

When the valve 54 is adjusted so that the slot 51 registers with thepassages 52 and 53, then such passages will be in communication with thepassage 44 and iluid can pass from the chamber \3| to the chamber 32through the passages 43 and 45, the chamber 41, the passage 64, thechamber 65, passages 61, 52, 44 and 42. Likewise with the valve 54regulated as just stated, uid can move from the chamber 32 to thechamber 3| through passages 42, 44 and 52, the chamber 41, and passages46 and 43 and it can also iiow from the passage 44 through the passage53, the chamber 46, and the passages 48 and 43. Small rebound verticalmovements of the wheel supporting structure and the i'rame relativelywill cause the piston 34 to move toward the left, as viewed in Fig. 3,creating pressure against the iluid in the shock absorber to open thevalve 56 so that small flow can pass thereby and, under suchcircumstances,

the spring 62 will not permit opening of the valve 6|. When suchrelative vertical movement obtains greater proportions, then the piston34 will create suiicient pressure against the uid in the shock absorber32 to open both valves 6| and 56. When the piston 33 is moved toward theright, as viewed in Fig. 3, it will force the valve 68 open so that flowwill be had, as above described. Movement of the piston 34 toward theleft will take place on rebound movement of the wheel supportingstructure and the frame relatively, whereas movement of the piston 33toward the right will take place on compression or movement of the wheelsupporting structure and the frame. By adjusting the screw plugs 49, 50and 66 axially, the spring force which must be overcome by iluidpressure to open the associated valves can be ad- .lusted.

The valve 1| is interposed in the passage 53 and one end is formed witha pair of oppositely disposed milled grooves 12 in the periphery, suchgrooves extending in an axial direction. The milled end of the valve 1|is assembled short of the end of the chamber 13 so that iiuid can ilowaround the end of the valve from one groove to the other and thusconnect the two parts of the passage 53. This valve is retained in itschamber by bushing 14 and one end 15 thereof projects beyond the casingfor the attachment of control mechanism. By turning the valve 1|, thesize oi' the passage 53 communicating with the slots 12 can be adjustedand thereby regulate the iiow of fluid so that the resistance. oiieredto relative movement between the wheel supporting structure and the mainframe can be varied.

When the valve 54 is turned so that the slot 51 does not register withthe passages 52 and 53,

then there can be no ow therethrough from the chamber 3| to the chamber32 or vice versa. In order to relieve the pressure developed by severeshocks occurring when this valve 54 is closed to the passages 52 and 53,I provide another circuit connecting with the passage 44 through meansof the circular groove 56 around the valve 54. Communicating with thevalve chamber 5| and the groove 56 is a passage 16 terminating in achamber 11 closed at the exterior by an axially adjustable plug 18. Thischamber communicates with the passage 45 which forms a continuation oi.'passage 43. Another passage 16 leads from the passage 18 to a chamber 80which is closed at its outer end by an axially adjustable screw plug 8|.The chambers 80 and 11 are connected by a passage 82. In the chamber 11is a valve 88 having a head engageable with the shoulder of the casingforming the Junction between the passage 18 and the chamber 11, suchvalve being normally seated by a coil spring 84. A valve 85 normallyengages the shoulder forming the junction be-` tween the passage 82 andthe chamber 80, such valve being normally seated by the coil spring 86.

It will be observed that the valves 83 and 85 close in oppositedirections and hence fluid iiowing from the chamber 8| will move fromthe passage 45 into the chamber 11 through the passage 82, the chamber80, and the passages 18 and 18 where it will move into the passage 44around the groove 58 in the valve 54. The fluid owing from the chamber82 to the chamber 8| will move through the passages 42 and 44, aroundthe groove 55 in the valve 54 into the passage 15, past the valve 88'into the chamber 11, and through the passage 45 from which it will moveinto the chamber 8| through the passage 43. The springs 84 and -88 exerta high pressure to prevent opening of the associated valves so that highpressure by the pistons 88 and 84 will be required in order to open thevalves 88 and 85 to establish communication between the chambers 8| and82. This circuit, as before explained, is in reality a relief effectivewhen the flow is cut of! through the normal circuit due to shutting offcommunication between the passage 44 and the passages 52 and 58.

Mechanism is associated with the valve 1| so that it can be regulatedfrom the dash. On the end 15 of the valve extending from the casing isfixed an arm 81 and pivoted to such arm is a link 88 extendingrearwardly to arm 88 fixed on a rotatable cross shaft mounted betweenthe frame side sills I0. An operating lever 8| is fixed to the shaft 80and a link 82 connects such lever with a bell crank lever 88 mounted onthe dash. Another link 84 connects this bell crank lever with a secondbell crank lever v95 which is mounted on the dash above the first bellcrank lever. An operating rod 86 extends through the dash 86', withingrasp of the driver of the vehicle, and is connected to the bell cranklever 95 so that, upon reciprocation, the linkage between the bell cranklever and the arms 81 of the front shock absorbers will be moved to turnthe shaft 1|. The fluid flow through passage 58 is thus regulated tovary the resistance to vertical movement of the wheel supportingstructures and the frame relatively. Such mechanism is commonly known asthe ride control for motor vehicles.

The valve 54 is controlled by the brake operating mechanism and thearrangement is such that when the brakes are applied, the valves 54 willbe turned so that flow between the passage 44 and the passages 52 and 58is cut oli?. With the present type of suspension mechanism, there isconsiderable resiliency at the front end of the vehicle which results inthe frame diving downwardly toward the front wheel supporting structureswhen the brakesare applied. Through means of the control valves 54, theshock absorber resistancevwill be made such as to substantiallyeliminate this diving, there being provision made for relief in theshock absorbers in case extraordinary pressure is developed therein dueto the wheels encountering a sharp unevenness in the road while thevalves 54 vare closed. Each of the road wheels is equipped with a brakedrum, as

indicated at 81, and within each of these drums is a conventional typeof expanding and contracting band 88 controlled by a cam member. asindicated at 88. These cam control members are mounted on shafts |00which have arms |0| extending therefrom connected with brake rods |02.The front and rear brake rods at each side of the vehicle are connectedto a lever |08 xed on a rotatable cross shaft |04 carried by the sidesills of the main frame. A pedal |05 is mounted on a shaft |08 carriedby one of the side sills and link |01 connects the pedal with arm |08fixed on shaft |04 and a spring ||2 connected to the pedal and a sidesill manually maintains the brake mechanism in released position.Control arms |08 are fixed to the front brake rods |02 and extendforwardly therefrom where they are pivotallg,r .connected with arms ||0xed to the projecting ends 55 of the valves 54.

l As the front brake rods |02 are reciprocated by operation of thepedal, they transfer similar motion to the rods |08 which in turn movethe arms ||0 therewith and thus turn the valves 54. When the brakes arereleased, the slot 51 in the valves will be open to the passages 52 and58 but, when the brakes are applied, the valves 54 will be turned sothat the slots 51 no longer communicate with the passages 52 and 53 andtherefore iiow therethrough between the chambers 8| and. 82 is cut off.Under such circumstances, the shock absorbers become substantially rigidstructures and will prevent vertical movement of the wheel supportingstructures and the mainframe relatively so that diving of the main frametoward the wheel supporting structures is substantially eliminated uponapplication of the brakes.

Althoughthe invention has been described in connection with a specificembodiment, the principles involved are susceptible of numerous otherapplications which will readily occur to persons skilled in the art. Theinvention is therefore to be limited only as indicated by the scope ofthe appended claims.

What I claim is:

1. In a road vehicle, suspension means including fluid shock absorbershaving flow control valves, brake actuating mechanism, and meansconnecting the brake mechanism with the control valves, said connectingmeans regulating the valves to restrict fluid flow in the shockabsorbers upon brake applying operation of the mechanism.

2. A fluid shock absorber comprising a casing, fluid containing chambermeans in the casing, piston means movable in the chamber means,operating means for the piston means extending exteriorly of the casing,a fluid connection in the casing between the remote ends of the chambervtween the remote ends of the chamber means,

valve means associated with the connection to establish or shut off flowtherethrough, and brake control mechanism connected -to actuate saidvalve means.

4. A iiuid shock absorber comprising a casing,

iluid containing chamber means in the casing, piston means movable inthe chamber means, operating means for the piston means extendingexteriurly of the casing, a fluid connection in the casing between theremote ends of the chamber means, valve means in the casing operable toestablish or vshut oil' iiuid tlow through the connection, a by-pass inthe casing communicating with the connection, valve means in the by passoperable by high fluid pressure in either direction to establish owthrough the by-pass, and brake control mechanism connected to actuatesaid valve means.

y culating iluid within the shock absorber: valves 5. A duid shockabsorber comprising a casing, iluid containing chamber means in thecasing, piston means movable in the chamber means, operating means forthe piston means extending cxteriorly oi' the casing, a iluid connectionin the casing between the remote ends o!A the chamber means throughwhich iluid ilows between the chambers, valve means in the casingoperable to establish or shut oil' iluid ilow through said connection,passage means in the casing communieating with thev connection toprovide a relief around said valve when shut oil, spring pressed valvemeans closing in two directions and opening in response to high fluidpressure. and mechanism responsive to checking and releasing of thevehicle speed to control said valve means.

6. A iluid shock absorber comprising a casing, iluid containing chambermeans in the casin, piston means movable in the chamber means,operataing means for the piston means extending exteriorly oi' thecasing, a iluid connection in the casing between the remote ends of thechamber means, valve means in the casing operable to establish or shutoil! iluid ow through the connection, a second valve in said connectionadjustable to regulate the volume oi' iluid ilowing through said passagein a given length oi time when the ilrst mentioned valve is open, andbrake applying mechanism connected to control saidv valve means.

7. A iluid shock absorber structure comprising a casing, fluidcontaining chamber means in the casing, piston means movable in thechamber means, operating means i'or the piston means extendingexteriorly of the casing, a fluid connection in the casing between theremote ends o! the chamber means, valve means extending into the casingturnable to establish or shut oi! fluid ilow through the connection, andbrake applying mechanism connected to the portion of said valve meansextending exteriorly of the casing and operable to turn the same.

8'. A hydraulic shock absorber for a vehicle having abraking systemactuated by a brake lever, comprising, in combination, means forcirculating iluid within the shock absorber; devices,

leach responsive to a diilerent degree of iluid pressure to permit iluidcirculation; and means actuated by the brake lever for renderingeiIective only that device which requires the greatest degree oi fluidpressure to provide for iluid circulation during the application oibraking forces.

9. lA hydraulic shock absorber i'or a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means for ciriorcontrolling iluid ilow; a control valve normally permitting` duid toilow to all of said valves, but adapted to be actuated by the brakelever, when applying braking forces, to shut oi! the iluid iiow tocertain of said valves.

10. Ahydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating uid within the shock absorber; devices, each adapted`tooiler a diil'erent degree of restriction to iluid circulation; and meansactuated by the brake lever when applying braking forces, for renderingei'lective only those two devices which oifer the two greatest degreeso! restriction to the ilow\ of fluid.

1l. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating iluid within the shock absorber; iluid now control devicesadapted to be actuated to permit fluid circulation at diilerent fluidpressures; and means normally directing iluid to all of said devices,but adapted to be actuated by the brake lever when applying brakingforces, to shut oil' iluid now to certain ot the low pressure iluid ilowcontrol devices.

12. A hydraulic shock absorber i'or a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating iiuid within the shock absorber; a plurality of iluid i'lowcontrol devices adapted, in response to iluid pressure, to permit iluidcirculation, certain of said devices acting in. response to a low fluidpressure, others in response to a higher fluid pressure and still othersin response to a still higher iluid pressure; and means adapted to beactuated by the brake lever, when applying braking forces, to permitiluid to ilow only to those devices requiring the 'two highest degreesof iluid pressure to permit iiuid circulation.

13. A hydraulic shock absorber i'or a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating fluid withinthe shock absorber; spring loaded valves forrestricting uid circulation; and a valve, normally rendering all of thespring loaded valves eil'ective; but adapted to be actuated by the brakelever to render some of said spring loaded valves ineffective.

14. A hydraulic shock absorber for a. vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating iluid within the shock absorber; a plurality of springloaded valves, certain of which restrict iluid ilow to a greater degreethan others; and a. valve normally directing iiuid flow to,all of saidvalves, but adapted to be actuated by the brake lever to permit iluid toflow to only two of said valves.

15. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising,incombination, means forcirculating iiuid within the shock absorber; valves for controllingiluid circulation; springs urging said valves into uid ilow restrictingpositions, certain oi' said springs exerting a greater pressure upontheir respective valves than others; and a nuid ilow controlling valve,normally directing iiuid flow to all of the valves, but adapted to beactuated by the brake lever when moved to brake applying position, todirect fluid ilow only to the two valves having the springs which exertthe greatest pressure. Y

16. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising in combination, means forcirculating iluid within the shock absorber; iluid tlow control devices;brake pedal actuated means for rendering only certain oi' said devicesetfective; and manually operated means for moditying the control of thefluid flow by one of said devices.

17. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating uld within the shock absorber; a plurality of fluid flowcontrol devices, each adapted to permit fluid circulation in response toa different degree of fluid pressure; brake lever actuated means forshutting oi fluid ilow to the devices requiring a fluid pressure below apredetermined degree to open them, while braking forces are beingapplied by said lever, and manually actuated means for modifying theflow of uid to one of said devices when the brake lever controlled meansis open.

18. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake Ilever, comprising, in combination, means forcirculating fluid within the shock absorber; a plurality of springloaded valves, adapted to be actuated at different fluid pressures topermit fluid circulation; a control valve adapted to be actuatedmanually to modify the flow of fluid to one ,of the lighter pressurevalves; and another control valve adapted to be actuated by the brakelever when applying braking forces, for discontinuing the flow of fluidto the first mentioned control valve and to all excepting two of theheaviest pressure spring loaded valves.

19. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, said shock absorber being adapted to controlthe approaching and separating movements of the vehicle frame and wheelsuspension, comprising, in combination, a casing providing a adapted tobe actuated to shut olf the uid ilow i through certain ducts and permitfluid to flow from each displacement chamber to only one fluid flowcontrolling means of said chamber, in response to the operation of .thebrake lever to apply braking` forces.

20. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever. said shock absorber being adapted to controlthe approaching and separating movements of the vehicle frame and wheelsuspension, comprising, in combination, a casing providing a cylinder inwhich a piston forms two fluid displacement chambers; ducts connectingsaid chambers; uid flow controlling devices in said ducts, adapted, inresponse to predetermined fluid pressures in said chambers, to providefor the transfer of fluid between the chambers; and means normallymaintaining all of said devices in the fluid circuits, but adapted to beactuated by the brake lever when braking forces are applied, to shut oiliiuid flow to all but two of said devices, said two including a fluidflow control device for each displacement chamber.

2l. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, said shock absorber being adapted to controlthe approaching and separating movements devices requiring greater fluidpressure than others to render them effective tn provide fluid flow; andmeans normally directing fluid iiow to all of saidldevices, but adaptedto be actuated by the brake lever when applying braking forces,

to shut od fluid flow to the devices requiring the lesser iiuidpressures to open them and direct fluid flow from each displacementchamber to a device requiring the greatest iluid pressure to open it.

22. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, said shock absorber being adapted to controlthe approaching and separating movements of the vehicle frame and wheelsuspension, comprising, in combination, a casing providing a cylinder inwhich a piston forms two iiuid displacement chambers; the first in whichthe fluid has pressure exerted upon it as the wheel suspension andvehicle frame move toward each other on the compression stroke and thesecond in which pressure is exerted upon the fluid upon the reversemovement of the Wheel suspension and frame or rebound stroke; ductsconnecting said chambers; two uid ilow control devices normallypreventing fluid flow from the first into the second displacement'chamber one of said devices opening to permit fluid flow at a lowerfluid pressure in said iirst chamber than the other; a plurality offluid ow control devices normally preventing fluid flow from the saidsecond into the said rst displacement chamber, each device requiring adifferent fluid pressure in said second chamber to open it; and means,

' normally maintaining all of said ducts open, but

adapted to be actuated by the brake lever when it is moved to applybraking forces, to keep open only such ducts that lead from eachdisplacement chamber to its fluid flow control device requiring thegreatest fluid pressure to open it.

23. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, said shock absorber being adapted to controlthe approaching and separating movements of the vehicle frame and wheelsuspension, comprisi'ng, in combination, a casing providing a cylinderin which a piston forms two fluid displacement chambers; the rst inwhich the fluid has pressure exerted upon it as the wheel suspension andvehicle frame move toward each other on the compression stroke and thesecond in which pressure is exerted upon the fluid upon the reversemovement of the wheel suspension and frame or rebound stroke; ductsconnecting said chambers; two uid ow control devices normally preventingfluid flow from the first into the second displacement chamber one ofsaid devices opening to permit fluid ow at a lower fluid pressure insaid rst chamber than the other; a plurality of fluid iiow controldevices normally preventing fluid flow from the said second into Ithesaid first displacement chamber, each device requiring a diierent fluidpressure in said second chamber to open it; a valve adapted to beactuated manually to modify the uid flow from the said second chamber tothe fluid flow control device, requiring the least pressure in saidchamber to permit a fluid flow therefrom; and a brake lever actuatedvalve. for controlling the iiuid ilow between the chamber whereby huidfrom each chamber is directed only to the iiuid ilow control device oieach chamber that requires the greatest fluid pressure to permit a flowfrom the respective chamber during the application of braking forces.

24. A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising, in combination. means forcirculatlng iluid within the shock absorber; tluid ilow control devices,means normally rendering all o! said devices eilective, but adapted tobe actuated by the brake lever when applying braking forces, to rendercertain o! said devices ineilective to control fluid now.

25. -A hydraulic shock absorber for a vehicle having a braking systemactuated by a brake lever, comprising, in combination, means forcirculating fluid within the .shock absorber; means for controlling saidiluid circulation; and means adapted to be actuated by the brake leverfor rendering only certain of said controlling means elective to permituid circulation.

26. In combination a vehicle brake, a wheel motion damper, andinterconnecting means between the brake and the damper for changing ltherate of damping when applying the brake.

27. In combination a vehicle brake, a hydraulic shock absorber, andinterconnecting means between the brake and the shock absorber forchanging the damping rate when applying the WALTER R. GRIBWOLD.

